title: Defensive sesterterpenoids with unusual antipodal cyclopentenones from the leaves of Leucosceptrum canum.
abstract: Two novel sesterterpenoids, leucosceptroids C (1) and D (2), possessing unusual antipodal cyclopentenones while maintaining the stereochemistry and functionality of the tricyclic cores, were discovered from the leaves of Leucosceptrum canum (Labiatae). Their structures including absolute stereochemistries were determined by comprehensive NMR, MS, and single-crystal X-ray diffraction analyses. The potent antifeedant activity of 1 against the generalist plant-feeding insect Helicoverpa armigera (EC(50) = 0.017 μmol/cm(2)) suggested them to be new defensive sesterterpenoids of L. canum.
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, PR China.
authors.forename: Shi-Hong
authors.initials: SH
authors.lastname: Luo
authors.forename: Lin-Hong
authors.initials: LH
authors.lastname: Weng
authors.forename: Ming-Jin
authors.initials: MJ
authors.lastname: Xie
authors.forename: Xiao-Nian
authors.initials: XN
authors.lastname: Li
authors.forename: Juan
authors.initials: J
authors.lastname: Hua
authors.forename: Xu
authors.initials: X
authors.lastname: Zhao
authors.forename: Sheng-Hong
authors.initials: SH
authors.lastname: Li
mesh_terms: D000818:Animals; D003500:Cyclization; D003517:Cyclopentanes / Q000737:chemistry* / Q000494:pharmacology; D019686:Lamiaceae / Q000737:chemistry*; D007915:Lepidoptera / Q000187:drug effects; D008958:Models, Molecular; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry; D054830:Sesterterpenes / Q000737:chemistry* / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D003517:Cyclopentanes; D054830:Sesterterpenes; C013905:cyclopentenone